Characterization and a role of Pseudomonas aeruginosa spermidine dehydrogenase in polyamine catabolism

Abstract

Pseudomonas aeruginosa PAO1 has two possible catabolic pathways of spermidine and spermine; one includes the spuA and spuB products with unknown functions and the other involves spermidine dehydrogenase (SpdH; EC 1.5.99.6) encoded by an unknown gene. The properties of SpdH in P. aeruginosa PAO1 were characterized and the corresponding spdH gene in this strain identified. The deduced SpdH (620 residues, calculated M r of 68 861) had a signal sequence of 28 amino acids at the amino terminal and a potential transmembrane segment between residues 76 and 92, in accordance with membrane location of the enzyme. Purified SpdH oxidatively cleaved spermidine into 1,3-diaminopropane and 4-aminobutyraldehyde with a specific activity of 37 units (mg protein) "1 and a K m value of 36 mM. The enzyme also hydrolysed spermine into spermidine and 3-aminopropanaldehyde with a specific activity of 25 units (mg protein) "1 and a K m of 18 mM. Knockout of spdH had no apparent effect on the utilization of both polyamines, suggesting that this gene is minimally involved in polyamine catabolism. However, when spdH was fused to the polyamine-inducible promoter of spuA, it fully restored the ability of a spuA mutant to utilize spermidine. It is concluded that SpdH can perform a catabolic role in vivo, but P. aeruginosa PAO1 does not produce sufficient amounts of the enzyme to execute this function.

Comparative single-cell genomics reveals potential ecological niches for the freshwater acI Actinobacteria lineage

“…Other transporters that the 11 acI SAGs have in common, include ABC-type transporters for ribose/xylose/ arabinose/galactoside, polyamines, dipeptides and branched-chain amino acids ( Table 2). The polyamine transporters are likely being used for putrescine uptake, as the SAGs harbor downstream pathways for its eventual conversion to succinate via the transamination pathway (Dasu et al, 2006;Chou et al, 2008); (Figure 2). Genes for the uptake of carboxylic acids in acI-A1, acI-A7 and acI-B1 were not found in any of the sequenced genomes, consistent with MAR-FISH-based studies (Buck et al, 2009;Salcher et al, 2013).…”

Diatom frustules as a biomaterial: effects of chemical treatment on organic material removal and mechanical properties in cleaned frustules from two Coscinodiscus species

“…Degradation products of various organic compounds are often determined using fluorometric analyses: Chlorophyll easily degrades to pheophytin in contact with acids or increasing temperature, and pheophytin shows red fluorescens [42] . Peroxidation of membrane lipids has been observed using fluorescence detection [43] , and Dasu et al [44] studied enzymatic polyamine catabolism using HPLC with fluorescence detection. Absence of fluorescence is therefore an indicator of efficient removal of organics.…”

Functional Characterization of Seven γ-Glutamylpolyamine Synthetase Genes and the bauRABCD Locus for Polyamine and β-Alanine Utilization in Pseudomonas aeruginosa PAO1

“…Without ␥-glutamylation, spermidine dehydrogenase encoded by the spdH gene was reported to catalyze oxidative cleavage of Spd into DAP and 4-aminobutyraldehyde, as well as spermine, into Spd and 3-aminopropanaldehyde (5). However, synthesis of this enzyme was not inducible by exogenous polyamines, and the spdH knockout mutant grew normally on Spd and spermine.…”